Stabilized concentrated photographic developing compositions



Patented Jan. 2, 1945- STABILIZED CONCENTRATED PHOTO- GRAPHIC DEVELOPING COMPOSI- TIONS George A. Dawson, -'Stelton, N. 3., assignor, by mesne assignments, to E. I. du Pont de Nemours & Company, Wilmington, Deh, a corporation oi Delaware No Drawing. Application April 16, 1941,

Serial No. 388,885

6 Claims.

This invention relates to photographic developing solutions and to their preparation. More particularly it relates to highly concentrated photographic developing solutions and to their preparation. Still more particularly it relates to concentrated developing solutions containing a high percentage of developing agent,

alkali metal carbonate, and water-soluble sulfite', I

and at least'3 parts by weight of a crystallization inhibitor in each 100 parts by volume of solution. When the metric system of measurement is employed, a part by weight is then a gram and a part by volume is a milliliter. It also relates to the utilizationof such photographic developers.

An object of this invention is to provide a satisfactory developer solution containing a high concentration of active ingredients. A further object is to provide such a solution which does not form crystals or precipitates on standing under ordinary storage conditions. A still further object is to provide a concentrated developer solution which is stable under abnormal tem-,

perature conditions and particularly at temperatures down to 32 F. Another object is to stabilize concentrated developing solutions in a practical manner with economical materials. Yet another object is to stabilize concentrated developing solutions which can be diluted with as much as 3 to' 4 volumes of water and produce an energetic developer for radiographs. Still further objects will be apparent from the following de-.

scription'. l

Concentrated photographic developing solutions capable of being diluted with 2 to 3 volumes of waterfor'preparing the actual working ple-' veloper solutions are known. Many commercial forms oi. such concentrated developers have appeared and, in'general, they contain methanol as the crystallization inhibitor. This alcohol has a number of disadvantages in'that it causes developer streaks, has an objectionable odor, causes hardening of gelatin and sometimes surface development.

. The concentrated developers of'theprior art in general contain, however, no more than ap- I proximately 350 grams per-liter of solids. It'is well known inphotographic developer-and development practices that developers forX-ray films require overall higher concentrations of active ingredients than those for the ordinary motion picture film. A primary reason for the 'requirement of higher concentratic ms of ingredients in X-ray developers is that thereis a consider- --ably greater amount of silver salts to be reduced asmuch as developers for x-ray film must conof these average type of developers so that one tain relatively higher concentrations of active ingredients, concentrated solutions of developers of such an order of concentration that they can be diluted with 3 to 4 volumes of water to produce the working solution, present the problem of finding some means of inhibiting crystallization of the developers as they cool from the hot solutions representing their state during preparation. An allied problem also is to prevent crystallization when a developer is chilled below normal temperatures while in'storage, transit, etc.

An ideal developer would be one comprising active ingredients which are all liquids in the natural state, all miscible with each other and all soluble in water orin one of the other constituents. Such a developer would. then be of maximum concentration and could bevdilutedwith large volumes of water to prepare the working developer solution which is relatively dilute. Inasmuch as the majority of the usual essential constituents of developers are solids, the nearest approach to the ideal developer is one repre senting the highest concentration of active solids which will remain ina water-clear solution. v

In order to show the order of concentration of constituents required in developers, the following table summarizes the average concentration ranges of the working solutions of three commonly used types of developers:

If it is desired to' prepare concentrated solutions volumeof stock solution can be diluted with 3 volumes of water to make diluted, working solutions containing the concentrations set out in the above table, the following total concentration. of active ingredients has been found neces- From this data it is seen that developers for 2;-

z ray emulsions contain the highest concentration of active constituents and thus present the most difficult problem of preparing in concentrated form.

It has been found that the above objects may be accomplished and a satisfactory concentrated developer solution prepared co taining at least 40% by weight of total solids by having present at least 15% of a water-soluble sulfite and at least 3% by weight of a crystallization inhibiting compound containing an ionizable hydroxyl group and being further characterized by the fact that a normal solution at 18 C. exhibits a degree of ionization of at least 60%. In the above and all following instances it is understood that the quantities expressed are parts by weight of solid per 100 parts by volume of solution.

The novel concentrated developer solutions of the invention contain a large amount of a developing agent, a large amount of preservative, and a large amount of accelerator in addition to various other ingredients such as restrainers, etc. and at least 3% of a crystallization inhibiting compound, preferably from 3% to 6% of an alkali metal hydroxide.

In a more limited aspect the concentrated aqueousv developer solutions contain from 425 to 565 grams per liter of activeingredients in the amounts set forth in the following table:

TABLE III I Grams per liter Reducers 40 to 60 Accelerators 160 to 195 Preservatives 170 to 200 Restrainers 25 to 50 Crys. inhibitors 30 to 60 The resulting solutions are stabilized against crystallization during storage or shipment over a wide range of temperature including temperatures slightly above freezing, e. g. 35 F.

' While alkali metal hydroxides are preferred as crystallization inhibitors, other bases which have a high degree of ionization and provide hydroxyl' ions in excess of those produced in the developing solution by hydrolysis or interaction of components can be used. Suitable additional inhibitors include hydrocarbon substituted-ammonium hydroxides and sulphonium hydroxides.

The novel concentrated photographic developer solutions hereof can be prepared by admixing the various "components in any desired manner. It is generally preferable to first dissolve or disperse the metol having the formula:

[llO-O-NElCH41HaSO4 when it comprises the developing agent in a mod-- erate amount of water, then the sodium sulfite,

then hydroquinone and then the remaining ingredients.

The invention will now be further illustrated,

" but is not intended to be limited'by the following specific examples which describe various practical developer solutions.

EXAMPLE II I p-Aminophenol hydrochloride grams 30 Chlor-Quinol do 6 Sodium carbonate (Na2COs-H2O) do 130 Potassium sulfite do 200 Sodium bromide do 40 Potassium hydroxide"; ..do 60 Water to make, liter 1 i0 EXAMPLE III Monoethyl-p-animonphenol sulfate 1 g grams l8 Quinol do 25 Potassium carbonate (86%) ..do 1 10 Sodium sulfite (desiccated) doi 200 Potassium bromide do 37 Potassium hydroxide do 35 Water to make liter 1 EXAMPLE IV Monomethyl-p-aminophenol sulfate grams .18 Quinol do 29 Potassium carbonate (86%) do 180 Sodium sulfite (desiccated) do 190 Potassium br do 32 Potassium hydroxide ..-do 38 Water to make liter 1 V Exmrm v Monomethyl-p-aminophehol sulfate grams 18 Quinpl do 29 Potassium carbonate (86%) .do 170 Sodium sulfite (desiccated) do 190 Potassium bromide do 32 Sodium hydr do 30 40 Water to make liter 1 EXAMPLE VI Pyrogallol grams.. Sodium carbonate (NaiCOa-HaO) do 195 Potassium sulfite do 200 Potassium bromide do Sodium hydroxide do 30 'Water to make liter 1 In'place of one or both of the specific develop- 50 ing agents set forth in the above examples may be substituted one or more other developing agents in such an amount-that the total is within the range of about 40 to about 65 grams per liter. The particular type of developing agent chosen as depends somewhat on the result desired. Suitable other agents include the aminophenols, poly phenols, and arylene polyamines such as, for ex-. ample, methyl-p-amino-phenol; 2-amino-5-hydroxy-toluenej methyl-o-aminophenol; 4-ami-' no-carvacrol; p-hydroxy-phenylglycine; p-hy- Exam: I

Monomethyl-p-aminophenol sulfategrams-.. 20 Quinol 1,4-dihydroxy benzene do 30 Potassium carbonate 186%) do 110 Sodium sulfite (desiccated) do 200 Potassium bromide do 35 Potassium hydroxide"; do 40 Water to make "L liter l no 2 -.\3 6 disulfonic acid. Mixed developing agents such as the combination of 1 mol of 4-hydroxy-phenol and 2 mols of methyl-p-aminophe- 1101 or 2 mols of methyl-o-aminophenol may also be used. The aminophenols and arylenepolyamines are used preferably in the form of their salts, such as the acid sulfates, hydrochlorides,

oxalates and'sulfonates. In addition'thedevelaaeaace oping agents of each of the respective examples may be interchanged in any desired manner.

The specific crystallization inhibitors, that is,

the hydroxides, described in the respective exam-' ples can be interchanged in any desired manner.

Likewise, oneor more alkali metal hydroxides may be used. As an additional suitable hydroxide remain clear and stable during storage and shipmention is made of lithium hydroxide. Potas sium and sodium hydroxide, however, are preferred as the alkali metal hydroxide in each 01 the compositions. Other suitable compounds which provide a suitable amount or supply of hydroxyl ions and can be substituted for all or a part of the specific hydroxides of the above examples include hydrocarbon substituted ammonium and sulfonium hydroxides, e. g. trimethylbenzylammonium hydroxide, tetramethyl ammonium hydroxide, tetraethylammonium hydroxide, trimethyl methylolammonium hydroxide, trimethyl brominethylammonium hydroxide, trimethylcyclohexylammonium hydroxide, dimethyl isobutylammonium hydroxide, triethyl alpha naphthylammonium hydroxide andNzN-diethyl piperidinium hydroxide, etc., trimethylsulphonium hydroxide, triethylsulfonium hydroxide, dimethylethylsulfonium hydroxide, benzyldimethylsulionium hydroxide, propyldiethylsulfonium hydroxide and isobutyldimethylsulfonium hydroxide, etc. Of these, trimethylsulphonium hydroxide is-preferred.

In place of all or a part of the specific preservatives .set forth in' the above examples which, oi course, can be interchanged in any desired manner, can be substituted one or more other sulfites, bisulfites, etc. Suitable additional compounds of this type include lithium, potassium' and pentavalent nitrogen salts of sulturous acid, e. g. tri-.

ethanolamine-, morpholine.-, teramethylammonium, and trimethylbenzylamonnium-sulfltes. A portion of the sulfites can be replaced by alka metal bisulfites and meta bisulfites.

Various other accelerators can likewise be substituted for all or a portion of those listed in the specific examples. Thus, the particular alkali metal carbonates of the respective examples can be interchanged in any desired manner. Other alkaline carbonates which present a source of reserve alkali which will maintain the alkalinity balance of the solution include lithium carbonate. Potassium and sodium carbonateahowever, are preferred.

Similarly, in place of the specific restrainers of the above examples which can be interchanged in any desired manner can be substituted one or more other compounds oi! this type. Suitable other compounds include sodium and lithium veloper solution containing from 40 to 60 grams bromides and chlorides, potassium chloride, etc.

However, potassium bromide is preferred.

The concentrated developer solutions hereof have considerable utility in the arts. They may be diluted with several volumes of water and used for developing various types of photographic, including radiographic films and plates. Upon dilution with 2 to 3 volumes of water, they are especially useful for the development 01- radiomphic elements, e. g. films and plates. In fact, this use constitutes their most important and preferred commercial application.

This invention has a numberot distinct advantages. the most important oi. which is thatit permits the preparation oi! stabilized concentrated developing solutions containing in excess of 425 grams 0! active A further advantage is that such solutions will ment and are unaffected by temperatures as low as 35 F. This immunity to precipitation makes it possible to use any part of such a solution by diluting it with 2 to 3 times its volume of water which would be impossible if even a small fraction of the dissolved materials were precipitated. A still further advantage is that the invention permits the use of concentrated solutions suitable for dilution with 2- or '3 times their volumeof water to form developing baths for treatment of radiographic film. This is particularly notable in view of the high concentration of dissolved ingredients found in the working strength of baths for such processing. Y

As many apparently widely difierent embodi- Y ments of this invention may be made without dean alkali metal carbonate and a water-soluble I sulfite in each liter of solution stabilized by the presence of from 30 to grams of an alkali metal hydroxide in each liter of solution, wherein water is the only solvent. I

' 2. A concentrated, aqueous, photographic developer containing from 425 to 565 grams of active ingredients comprising a developing agent, an alkali metal carbonate and a water-soluble sulfite in each liter of solution stabilized by the presence of from 30 to 60 grams of a hydroxide having a high dissociation constant, taken from the group consisting oihydrocarbon substituted sulionium and ammonium hydroxides in each liter of solution, wherein water is the only solvent.

3. A concentrated aqueous photographic deof a photographic developing agent, to 195 grams of a water-soluble carbonate, from to 200 grams of a water soluble sulfite, from 25 to 50 gramsoi a restrainer and from 30 to 60 grams of a crystallization inhibitor comprising a base yielding a large amount of hydroxyl ions in each liter of solution. I

4. A concentrated aqueous photographic developer solution containing from 40 to 60 grams of a. photographic developing agent, 160 to'l95 grams of a water-soluble carbonate, from 170 to 200 grams of a water soluble sulfite, from 30 to 60 grams or an alkali metal hydroxide in each liter of solution. r

- 5..A concentrated aqueous photographic developer solution containing from 40- to 60 grams 01' a photographic developing agent, 160 to grams of an alkali metal carbonate, from 170 to 200 grams or an alkali metal sulfite, from 25 to '50 grams -or an alkali metal bromide and from 30 to 60grams oian alkali metal hydroxide in.each

liter of solution.

6. A concentrated, aqueous, photographic developer containing from 425 to 565 grams of active ingredients comprising a developing agent,

ln'gredlentsper liter ot solution.

an alkali metal carbonate and a water soluble sul-.

fite stabilized by from 30-to 60 grams of an alkaline crystallization inhibiting base having a high degree of ionization and yielding a large amount.

of hydroxyl ions in aqueous solution, in each liter of solution wherein water is the only solvent. I GEORGE A. DAWSON. 

